Is topical treatment with Crystavet® an effective treatment of Malassezia overgrowth in dogs? : – a pilot study.

Sammanfattning: Malassezia spp. are commensals of the canine skin flora. Opportunistic skin infections involving overgrowth of Malassezia are often found in intertriginous areas or associated with one or several underlying medical conditions affecting the host defence of the skin barrier. Symptoms include pruritus, erythema, alopecia, lichenification, hyperpigmentation, scaling and moist skin surface with a greasy, malodorous exudate. A diagnosis of Malassezia dermatitis is indicated when skin with cutaneous lesions and Malassezia overgrowth responds to antifungal therapy. Treatments available with the indication of Malassezia overgrowth include both systemic treatment with azole derivatives or allylamine and a wide variety of agents for topical treatment. Available topical treatment options include azole derivatives and antimicrobial agents, many of which lack sufficient evidence base. Therefore, the need for randomized, controlled trials evaluating topical antimicrobial agents available and marketed for Malassezia overgrowth is urgent. The purpose of this study was to evaluate the efficacy of a new topical product, Crystavet® (1% hydrogen peroxide, Bioglan, Malmö, Sweden), for the treatment of Malassezia overgrowth in a prospective, open, randomized, controlled study design using a split-body protocol. In total, 22 anatomically distinct skin areas from ten dogs were included. The efficacy of Crystavet was compared to a reference product of 4% chlorhexidine and evaluated based primarily on the reduction of Malassezia yeast obtained by cytology. Secondly, the efficacy was evaluated by quantitative culture of Malassezia spp., clinical skin lesion score and degree of pruritus pre and post treatment. Treatment with both Crystavet and the reference product reduced Malassezia population sizes and clinical parameters significantly, without any difference in efficacy noted between the products. No adverse reactions were recorded and owners rated the treatment as easy to perform. These results suggest that topical treatment with Crystavet (1% hydrogen peroxide) is effective and safe for the treatment of localized Malassezia overgrowth in dogs. The results also suggest that the antifungal efficacy of 1% hydrogen peroxide is similar to that of 4% chlorhexidine for Malassezia species. Further studies including a larger sample size are needed to confirm these results.